CoQn, n≦12 isoprene units, are found in the mitochondrian of every cell of nearly all types of verebrates. The Coenzyme Qn constitute one of the more important classes of compounds involved in the electron-transfer processes vital for the respiration system of verebrates. The Coenzyme Qn that contains ten isoprene units (n=10) is the redox carrier used by the human being. CoQ10 is a important antioxidant use by the celles to trap free radicals. Studies have shown that CoQ10 can exert efficacy in treating patients with mitochondrial disorders, and for the treatment of neurodegenerative diseases such as Parkinson's disease, Huntington's disease and amyotrophic lateral sclerosis.
2,3-dimethoxy-5-methyl-[1,4]benzoquinone of formula (I), also known as coenzyme Q0 (CoQ0) has been been shown to be a valuable building block for the synthesis of coenzymes Qn (with n=1-12)

Previously reported syntheses of the ubiquinones (Moiseenkov, A. M.; Veselovskii, A. B. Pharm. Chem. J. 1992, 26, 508) involve multi-step processes, (Anslow, W. K.; Ashley, J. N.; Raistrick, H. J. Chem. Soc. 1938, 439. (b) Hoffmann, F. (La Roche Co). Brit. Patent 889704, 1962), require large amounts of oxidizing agents, provide low yields, (Orita, H.; Shimizu, M.; Hayakawa, T.; Takehira, K. (Agency Ind. Sci. Techn., Japan). U.S. Pat. No. 4,952,712, 1990.) and in some cases toxic by-products are formed. (Matsumoto, M.; Kobayashi, H. J. Org. Chem. 1985, 50, 1766). In the synthesis of the simplest ubiquinone, CoQ0 (formula I), oxidation of 3,4,5-trimethoxytoluene with various reagents, including Fremy's salt, ceric(IV) ammonium nitrate, H2O2 in HCO2H, meta-chloroperbenzoic acid or H2O2 in AcOH, and H2SO4, give 2,3-dimethoxy-5-methyl-[1,4]benzoquinone in only low yields. Matsumoto and Kobayaski (Matsumoto, M.; Kobayashi, H. J. Org. Chem. 1985, 50, 1766) reported the hexacyanoferrate-catalyzed oxidation of 3,4,5-trimethoxytoluene with H2O2, a more efficient process but still with moderate yields (<50%). Other methods for the synthesis of CoQ0 starting from highly functionalized aromatic starting materials such as vanilline, gallic acid, pyrogallol, and tetramethoxytoluene, are complex multi-step processes. More convenient oxidants, such as molecular oxygen and H2O2, have attracted considerable attention, although they are generally used in the presence of metal catalysts.